ABSTRACT Current strategies for treating type 1 diabetes via cell replacement are limited by a shortage of donor islets; human pluripotent stem cell (hPSC)-derived ? (hPSC-?) cells represent a promising solution to this dilemma. To improve current methodologies for the differentiation of hPSCs towards functional ?-cells, a comprehensive understanding of the molecular programs for the processes of endocrine development and ?-cells maturation is still required. Our preliminary studies suggested that integrin signaling and microenvironment stiffness play an integral role in coordinating islet and ?-cell development. The present proposal seeks to elucidate the role that integrin and microenvironment stiffness play in coordinating these complex processes. We aim to uncover the mechanisms of integrin signaling in controlling 1) endocrine cell fate decision, 2) islet development, and 3) ?-cell maturation. We will utilize a combination of pancreas-, islet-, and ?-cell-specific deletion mouse models to inactivate integrin subunit ?1 (Itgb1, a subunit essential for integrin signaling). We also aim to promote in vitro maturation of hPSC-? cells by controlling the microenvironments stiffness. To achieve this, we established a novel cell culture platform for temporal control of microenvironment stiffness. By culturing and differentiating the hPSC-? progenitors on this platform, we will elucidate the role which microenvironment stiffness plays on ?-cell maturation. Together, our study will provide a greater understanding of the role of integrin signaling and microenvironment stiffness in regulating ?-cell development. This will inform future functional hPSC-? generation strategies.